1. Field of the Invention
The present invention relates to plasma processing of semiconductor devices. More particularly, the present invention relates to an apparatus for integrating sensors and hardware controls used in a semiconductor manufacturing equipment, specifically, in a plasma etching system.
2. Background Art
Various forms of processing with ionized gases, such as plasma etching/deposition and reactive ion etching/deposition, are increasing in importance particularly in the area of semiconductor device manufacturing. Of particular interest are the devices used in the etching process. FIG. 1 illustrates a conventional inductively coupled plasma etching system 100 that may be used in the processing and fabrication of semiconductor devices. Inductively coupled plasma processing system 100 includes a plasma reactor 102 having a plasma chamber 104 therein. A transformer coupled power (TCP) controller 106 and a bias power controller 108 respectively control a TCP power supply 110 and a bias power supply 112 influencing the plasma created within plasma chamber 104.
TCP power controller 106 sets a set point for TCP power supply 110 configured to supply a radio frequency (RF) signal, tuned by a TCP match network 114, to a TCP coil 116 located near plasma chamber 104. A RF transparent window 118 is typically provided to separate TCP coil 116 from plasma chamber 104 while allowing energy to pass from TCP coil 116 to plasma chamber 104.
Bias power controller 108 sets a set point for bias power supply 112 configured to supply a RF signal, tuned by a bias match network 120, to an electrode 122 located within the plasma reactor 104 creating a direct current (DC) bias above electrode 122 which is adapted to receive a substrate 124, such as a semi-conductor wafer, being processed.
A gas supply mechanism 126, such as a pendulum control valve, typically supplies the proper chemistry required for the manufacturing process to the interior of plasma reactor 104. A gas exhaust mechanism 128 removes particles from within plasma chamber 104 and maintains a particular pressure within plasma chamber 104. A pressure controller 130 controls both gas supply mechanism 126 and gas exhaust mechanism 128.
A temperature controller 134 controls the temperature of plasma chamber 104 to a selected temperature setpoint using heaters 136, such as heating cartridges, around plasma chamber 104.
In plasma chamber 104, substrate etching is achieved by exposing substrate 104 to ionized gas compounds (plasma) under vacuum. The etching process starts when the gases are conveyed into plasma chamber 104. The RF power delivered by TCP coil 116 and tuned by TCP match network 110 ionizes the gases. The RF power, delivered by electrode 122 and tuned by bias match network 120, induces a DC bias on substrate 124 to control the direction and energy of ion bombardment of substrate 124. During the etching process, the plasma reacts chemically with the surface of substrate 124 to remove material not covered by a photoresistive mask.
Primary parameters such as plasma reactor settings are of fundamental importance in plasma processing. The amount of actual TCP power, bias power, gas pressure, gas temperature, and gas flow within plasma chamber 104 greatly affects the process conditions. Significant variance in actual power delivered to plasma chamber 104 may unexpectedly change the anticipated value of other process variable parameters such as neutral and ionized particle density, temperature, and etch rate.
In existing plasma etch systems, however, primary parameters are controlled through separate standalone controllers that do not directly communicate with each other in real-time. FIG. 2 illustrates a conventional plasma etching control hardware system. A TCP match 200 includes a TCP controller 202. A bias match 204 includes a bias controller 206. A pressure control valve 208 includes a pressure controller 210. An optical emission spectrometer (OES) or interferometer (INTRF) 212 includes an OES or INTRF controller 214. A VME chassis 216 communicates with standalone controllers 202, 206, 210, and 214 via serial links 218. Thus, reactor settings are controlled separately through standalone controllers with a relatively slow communication link between each other.
In plasma etching systems, a change in one of the parameters may affect the other parameters. For example, during a process, chemical reactions in the chamber cause the plasma impedance to vary affecting the power delivery, temperature, and pressure. Thus, elaborate discreet recipe steps need to be developed by an operator to effectively de-couple these effects. This generally limits the operating process window, and increases the processing time, affecting the plasma etching system throughput potential. Furthermore, the first wafer effect (the process of a first wafer within a same plasma reactor causes changes in the plasma reactor that affect subsequent processes), and the ever present process drift over time (plasma reactors used over a period of time lose their accuracy because of their prolonged usage) are also indications that the control of reactor settings do not solely control what happens inside the chamber and at the wafer.
A need therefore exists for a method and a device that would centralize all the controls with an open architecture allowing real-time communication between the various controllers. Such a device would allow an operator to significantly improve the stability and repeatability of the etch process, and eventually control the parameters directly relevant to the process therefore directly controlling wafer features.
A central controller for use in a semiconductor manufacturing equipment integrates a plurality of controllers with an open architecture allowing real-time communication between the various control loops. The central controller includes at least one central processing unit (cpu) executing high level input output (i/o) and control algorithms and at least one integrated i/o controller providing integrated interface to sensors and control hardware. The integrated i/o controller performs basic i/o and low level control functions and communicates with the CPU through a bus to perform or enable controls of various subsystems of the semiconductor manufacturing equipment.
A method for controlling a plurality of sensors and a plurality of control hardware for use in a semiconductor manufacturing equipment loads an application software onto a cpu board that is plugged in a bus. Sensors and control hardware are linked to electrical controllers that are mounted onto a single circuit board which occupies an address block in a memory space of the bus. The single circuit board is then plugged in the bus and the sensors and control hardware are controlled via the application software.